1. Field of The Invention
This invention pertains to non-pneumatic tires for mounting onto a rim, forming a wheel structure, and more particularly to a light weight, integrally molded tire/rim structure having the mechanical and riding performance characteristics of a conventional pneumatic wheel structure.
2. Prior Art
The present invention contemplates a new and improved tire and rim assembly which is simple in design, effective in use, provides a combination that has ride and wear characteristics that approximate, or are better than, a conventional pneumatic tire and wheel assembly, is lighter in weight than such pneumatic tire and wheel assembly, and can be manufactured at a significantly lesser cost.
Essentially solid, cavity free, non-pneumatic tires have been used for many years going back to as early as 1878 as set out in a British Patent No. 2,367 that shows a solid resilient tire and rim. A number of later patents also show non-pneumatic tire and rim combinations as, for example, British Pat. Nos. 3,432; 15,439; 20,186; and 27,224, French Pat. Nos. 338,920 and 367,981 and U.S. Pat. Nos. 1,056,976; 1,178,887; 3,533,662 and 5,229,047. Further, non-pneumatic tires are shown manufactured in earlier U.S. Pat. Nos. 4,855,096 and 4,943,323, that were co-invented by the present inventor. Which non-pneumatic tires have all been arranged for mounting onto a rim. Additionally, other earlier patents covering non-pneumatic tires, that include inner cavities, are shown in early British Patent Nos. 11,800 and 14,997 along with early U.S. Pat. Nos. 1,194,177 and 1,670,721. None of which solid non-pneumatic, or solid non-pneumatic tires that include cavities, have included a rim mounting where the tire is maintained to the rim so as to allow for tire inward or radial flexure into a void or open area between the tire inner circumference and rim wheel well to more nearly duplicate the ride action of a pneumatic tire.
In practice, non-pneumatic tires have the advantage of not going flat or experiencing a blow-out. Heretofore, however, this advantage has not outweighed the better cushioning and shock absorbing characteristics presented by a pneumatic tire. The tire and rim combination of the invention provide a wheel that will not go flat and still provides a cushioned shock absorbing wheel duplicating the ride qualities of a pneumatic tire.
Weight is an important criteria in a tire and wheel assembly. A disadvantage of the conventional pneumatic and/or prior art non-pneumatic tire and wheel assemblies is their excessive weight. This results from the two- and three-piece assembly of the tire and rim combination as well as the tire material used in prior art tire designs. Such excessive weight increases the overall weight of the vehicle, such as a bicycle, and hence, more energy is expended to propel the vehicle.
Heretofore, tires have generally utilized beads to hold the tire upon the wheel, and such beads usually are formed from high-tensile steel wire formed into inextensible hoops. The bead functions to anchor the plies of the tire together and to hold the tire on the wheel rim. The shape or flange of the bead conforms to the flange of the rim to prevent the tire from rocking, slipping or rolling off the wheel rim. While the beads have been successful in holding a tire on a rim they are an additional cost, add to the weight of the tire, and require additional manufacturing, assembly time, resulting in increased production costs. The invention provides a beadless non-pneumatic tire that is mounted to present an open area between the tire undersurface or inner circumference and the rim web or wheel well that the tire lower portion will flex into, providing ride cushioning that is like that of a pneumatic tire. The lack of a tire bead and the formation of a tire configured to fit into a rim to leave a void or open area between the rim web and tire undersurface presents a minimum tire volume thereby minimizing the amount of tire materials needed for tire manufacture, and presents a minimal weight of a tire and rim combination.
It is a principal object of the present invention in a non-pneumatic tire and its rim to provide a beadless mechanical lock mounting such that a tire lower area well flex into a cavity or open area between the tire inner circumference and the rim web or wheel well, cushioning forces as are directed into the wheel by expansion of the tire material into that cavity or open area.
Another object of the present invention is to provide pier supports formed around the rim web or wheel well ends for supporting the tire inner circumference ends so as to leave the tire circumference unsupported between its ends unsupported, providing for tire flexure under compressive load into a space or open area that is between the tire inner circumference and the rim web or wheel well surface.
Another object of the present invention is to provide a non-pneumatic tire and rim combination where the tire includes an interference mounting that is easily installed onto and is conveniently removable from the rim.
Still another object of the present invention is to provide, in addition to the tire and rim interference mounting, as required, a chemical lock that is applied to the opposing rim and tire surfaces to assist in maintaining the non-pneumatic tire on the rim.
Still another object of the present invention is to provide a non-pneumatic tire and rim combination that is light in weight and which non-pneumatic tire has superior wear and stability characteristics as compared to pneumatic tires.
In accordance with the present invention, a new and improved non-pneumatic tire that includes a beadless interference lock for maintaining it onto a rim, and also includes support ridges or piers that support the tire sides lower ends while leaving the tire inner circumference unsupported to flex freely into a cavity or open area between the rim web or wheel well and the mid-portion of the non-pneumatic tire inner circumference.
The preferred non-pneumatic tire is formed from urethane foam, preferably by a spin casting process, to include side wall grooves that are to seat within and provide an interference fit to the rim. The seating within the rim, in practice, has approximately a one (1.0) percent with flanges of a U-shaped rim, the rim flanges are perpendicular to the rim sides top ends and extend inwardly to receive the tire wall grooves, providing an interference fit and forming a mechanical lock of the tire to the rim flange that can be augmented with an adhesive, as desired.
The rim sides slope inwardly and terminate in junctions with the rim web or wheel well wherein are from continuous ridges, piers or steps that are to support the non-pneumatic tire inner circumference ends that are formed around the junctions of the tire side walls and inner circumference ends. So arranged, the tire inner circumference mid-section will be unsupported above the rim web or wheel well. The open area or space between the tire inner circumference and the wheel well surface is to receive a flow of the tire materials directed therein as the tire flexes in response to a compressive force exerted into the tire tread. The non-pneumatic tire thereby exhibits compression and rebound as it rolls over a surface, bumps over rocks and the like, providing a ride that is similar to that provided by a pneumatic tire.
Still other benefits and advantages of the invention will become apparent to those skilled in the art to which it pertains upon a reading and understanding of the following detailed specification.